over payment refund

On 8/10/2023 I paid my bill to reactivate my phones for missing my payment date.  I used the app and I was Instructed to pay $65 .... 50 plus the 15 dollar reactivation fee.  The app did not update correctly and told me I still had an outstanding balance of $50.  I then made a second payment.  The app refreshed and still indicated I had an outstanding balance.  So I again made another 50 dollar payment.  I now have $115 as account credit.  I contacted customer support and was told I cannot get the overpayment refunded and would need ro dispute the transactions with my bank.  I was also informed that if I did so my account would be canceled.  I am not asking for my total payment to be refund.  I want my overpayment refunded.  According to my account it says that amount is $115.  I am totally disappointed In the customer service I received.  I would like my overpayment refunded to my bank asap.  I have been a customer since 2018 and until now have not had any issues but this is making me question if I should stay a customer with cricket.  This overpayment was due to the app not functioning correctly and updating the amount due.  I was informed that there was no known issue and was basically told I was wrong and lying about what I experienced.  I was told that this was my mistake and due to the terms and conditions of paying online I could not get my refund after I was told they had no ability to do the refund because it's a prepaid service.  All I want is my account credit refunded to me without being told that disputing the charges would cancel me as a customer.  Please help me.